For completeness' sake, I'll note that multiple commands can be placed on a single line, separated by semicolons. Instead of writing a script, you could put the line 0 0 * * * /etc/init.d/apache2 stop ; perl /var/path/to/my/backup/script ; /etc/init.d/mysql restart ; /etc/init.d/apache2 start into your crontab. When the first command completes, the second one will run, and so on.

There might be line-length limitations in crontab, so I wouldn't go overboard and generate huge strings of commands.